Method of improving signal quality

ABSTRACT

A method for transmitting data is provided. The method includes receiving a service request for a standby subscriber terminal, such as when a call is placed to or from the standby subscriber terminal. The number of telecommunications channels carried by a trunk group is then changed, such as by increasing or decreasing the number of encoded telecommunications channels carried by the trunk group. The standby subscriber terminal is then assigned to one of the telecommunications channels of the trunk group.

CLAIM OF PRIORTY

The present application is a divisional patent application ofapplication Ser. No. 09/045,470, entitled “Method and System forWireless Telecommunications”, by Robert J. McGuire, filed Mar. 20, 1998,and now U.S. Pat. No. 6,131,039.

FIELD OF THE INVENTION

This present invention relates in general to telecommunications systemsand more particularly to a method and system for wireless datacommunications, including a system for dynamically allocating datachannels to trunk groups.

BACKGROUND

Wireless communications systems use electromagnetic radiation to carryencoded data between a transmitter and a receiver. In wirelesscommunication systems that include a central terminal that services alarge number of subscriber terminals, each with the capability toreceive and transmit data, it is necessary to efficiently use theelectromagnetic frequency spectrum to accommodate the largest number ofsubscribers.

For example, a wireless local loop system may be used to provide serviceto residential areas. Such environments are typically multi-pathenvironments, which are characterized by radio frequency signals beingreflected by intervening objects, such that a large number of duplicatesignals may be received at the receiver. In such environments, it isnecessary to perform additional signal processing to improve the qualityof the received signal.

In addition to the phenomenon of multi-path signal generation, radiofrequency licensing entities often allocate available radio frequencyspectrum space to telecommunications service providers in segments ofvarying bandwidth size. The number of users of the system also varies asa function of time, which can cause the signal quality to subscriberterminals that are remote from the central terminal to be degraded eventhough additional unused system capacity exists that could be used toimprove the signal quality. Existing systems and methods for datacommunications that are used in multi-path environments are not easilyreconfigured to accommodate changes in bandwidth, signal strength,number of users, or other variables. Therefore, it is difficult tooptimize the data communication systems for the service environment,number of users, licensing variables, and other variables.

SUMMARY OF THE INVENTION

Therefore, a system and method for wireless data communications arerequired that substantially eliminate or reduce the problems associatedwith conventional systems and methods for wireless data communications.

In particular, a system method for wireless data communications isrequired that allows the signal strength to users that are remote fromthe central terminal to be improved when additional system resources areavailable.

In accordance with the present invention, a method is provided fortransmitting data. The method includes receiving a service request for astandby subscriber terminal, such as when a call is placed to or fromthe standby subscriber terminal. The number of telecommunicationschannels carried by a trunk group is then changed, such as by increasingor decreasing the number of encoded telecommunications channels carriedby the trunk group. The standby subscriber terminal is then assigned toone of the telecommunications channels of the trunk group.

Another embodiment of the present invention is a system for transmittingdata. The system includes a central terminal coupled to atelecommunications network. The central terminal transmits and receiveschannels of data from the telecommunications network. The system alsoincludes a plurality of subscriber terminals. Each subscriber terminalis operable to transmit and receive a channel of data from the centralterminal. A trunk group having an effective radiated power level ismodulated by a first group of one or more data channels. The effectiveradiated power level may be increased or decreased as a function of thedistance between one or more subscriber terminals and the centralterminal. Another trunk group is modulated by another one or more datachannels. The effective radiated power level of the other trunk groupmay be increased or decreased as a function of the distance between theother group of one or more subscriber terminals and the centralterminal.

The present invention provides many important technical advantages. Oneimportant technical advantage of the present invention is a method forimproving the quality of data communications that allows the number oftelecommunications channels carried by a trunk group to be dynamicallyincreased and decreased. This dynamic assignment allows signal qualityto be improved when system usage is light.

Another important technical advantage of the present invention is asystem for transmitting data that allows the amplification power levelsof trunk groups to be dynamically assigned. Dynamic assignment of powerlevels between trunk groups allows power to be reassigned from trunkgroups that are servicing subscriber terminals that are near to thecentral terminal to trunk groups that are servicing subscriber terminalsthat are remote from the central terminal. Thus, the signal quality maybe improved for one channel without adversely affecting the signalquality of other channels.

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of the invention will be described hereinafter, by way ofexample only, with reference to accompanying drawings in which likereference numbers are used for like features and in which:

FIG. 1 is a diagram showing a wireless data communications system inaccordance with one embodiment of the present invention;

FIG. 2 is a radio spectrum utilization diagram embodying concepts of thepresent invention;

FIG. 3a is a diagram of an exemplary embodiment of power levels fortrunk group signals broadcast by a central terminal;

FIG. 3b is a diagram showing trunk group signal usage inside of aservice cell in accordance with the exemplary embodiment of the presentinvention;

FIG. 4a is a diagram of an exemplary embodiment of power levels fortrunk group signals broadcast by a central terminal;

FIG. 4b is a diagram showing trunk group signal usage inside of aservice cell in accordance with the exemplary embodiment of the presentinvention;

FIG. 5a is a diagram of an exemplary embodiment of power levels fortrunk group signals broadcast by a central terminal;

FIG. 5b is a diagram showing trunk group signal usage inside of aservice cell in accordance with the exemplary embodiment of the presentinvention;

FIG. 6 is a flow chart of a method for providing access to atelecommunications system in accordance with one embodiment of thepresent invention; and

FIG. 7 is a flow chart of a method for providing access to atelecommunications system in accordance with one embodiment of thepresent invention.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of a wireless data communications system 10 inaccordance with one embodiment of the present invention. System 10includes central terminals 12, subscriber terminals 14, and servicecells 16. Central terminals 12 communicate by radio frequencyelectromagnetic radiation with subscriber terminals 14. Each centralterminal 12 and subscriber terminal 14 is associated with a service cell16.

The effective radiated power from each subscriber terminal 14 iscontrolled via feedback from the associated central terminal 12 so as tomaintain the power level of the signal received at the correspondingcentral terminal 12 at a predetermined level, such as −90 decibels below1 milliwatt (dBm). Thus, the power level at each subscriber terminal 14is a function of the location of the subscriber terminal 14 relative tothe central terminal 12.

In a similar manner, the effective radiated power from each centralterminal 12 may be controlled as a function of the location of thesubscriber terminals 14 that are being serviced by the central terminal12 at any given time. For example, if the majority of active subscriberterminals 14 are located far from the central terminal 12, it may benecessary to increase the power of the signal radiated by the centralterminal 12. This may be accomplished by decreasing the number oftelecommunications channels that are being transmitted, such as toincrease power for the remaining channels, or by increasing the powerfor certain channels and decreasing the power for other channels. Inthis manner, the amplification power of the central terminal may beoptimized for use in serving the subscriber terminals of the cell.

FIG. 2 is a frequency diagram 18 for a data transmission system inaccordance with one embodiment of the present invention. Frequencydiagram 18 includes 3.5 MHZ frequency band 20, which is an inbound oroutbound radio frequency band modulated by suitable means to occupy apredetermined portion of the radio frequency spectrum. For example,frequency band 20 may be converted to occupy the radio frequencyspectrum between 2.259 and 2.2625 gigahertz in an outbound directionfrom the central terminal 12 to subscriber terminals 14, and to occupythe radio frequency spectrum from 2.434 to 2.4375 gigahertz in aninbound direction from subscriber terminals 14 to the central terminal12. Alternatively, frequency band 20 may be used in accordance withlicensing requirements for any suitable portions of the radio spectrumfrequency. Frequency band 20 is used for transmitting data from atransmitter to a receiver. For example, frequency band 20 may be used totransmit data from a single transmitter to a single receiver, from acentral transmitter to two or more receivers, or from two or moretransmitters to a central receiver.

Frequency band 20 is further divided into one slot of five trunk groups22, each of which occupy one 700 kHz band of frequency band 20. Eachtrunk group provides the necessary bandwidth for transmittingtelecommunications data by a suitable modulation techniques, such as toa group of subscribers. For example, code division multiple access, timedivision multiple access, quadrature phase shift keying, or othersuitable data transmission techniques may be used alone or incombination to encode and transmit data between the central terminal andthe subscriber terminals.

In addition, the use of two or more trunk groups allows a datatransmission system utilizing frequency diagram 18 to be easilyorganized in service areas and classes of service. For example, apredetermined number of trunk groups may be selected for provision ofIntegrated Service Digital Network service, while other trunk groups mayprovide dedicated 32,000 bits per second service and 64,000 bits persecond service. Alternatively, predetermined trunk groups may provideservice to predetermined areas, such that the effective radiated powerlevel of some trunk groups may be increased or decreased to better servethe subscriber terminals in the associated service area. The assignmentof trunk groups to service classes or service areas may also beperformed dynamically, when service in those classes or service areasare required.

In operation, a data communications system such as system 10 uses theavailable frequency spectrum in accordance with frequency diagram 18 inorder to facilitate communications between a central terminal 12 and aplurality of subscriber terminals 14. The system utilizing frequencydiagram 18 may include a single central terminal that is connected tothe public switched telecommunications network by copper conductor,optical fiber, radio waves, or other suitable means. The centralterminal is connected by radio waves to a suitable number of standbysubscriber terminals and to a suitable number of active subscriberterminals for each trunk group 22. By way of example and not bylimitation, the central terminal may be connected to 256 standbysubscriber terminals and to 28 active subscriber terminals.

The 28 active subscriber terminals may each receive a 32 kilobit persecond data stream that is encoded using a suitable wireless datatransmission encoding technique, and is transmitted between the centralterminal and the active subscriber terminals. Each 700 kHz trunk group22 operates independently of the other trunk groups 22. This structureallows the number of trunk groups 22 to be increased or decreased asappropriate to accommodate a portion of the radio spectrum allocated bythe licensing agency. In addition, the 700 kHz bandwidth may be furtherdivided into sub-carrier bands in order to provide for efficient use ofthe available amplification power for each 700 kHz band and to improvethe efficiency of data transmission in a multi-path environment.Depending upon the data transmission requirements of the wirelesscommunication system, a greater or lesser number of sub-carrier bandsmay be used.

In addition, each 700 kHz trunk group 22 may be amplified to varyinglevels or may be modulated to provide varying numbers oftelecommunications channels in order to provide additional control forthe provision of service to subscriber terminals 14. For example,central terminal 12 may increase the amplification of all channels ofcertain trunk groups 22 by up to 3 dB by decreasing the amplification ofthe channels in other trunk groups 22 by 3 dB. An additional 3 dB ofgain can also be provided to the channels of predetermined trunk groups22 by decreasing the number of channels carried per trunk group 22, suchas from 32 to 16. The number of channels and amplification power levelsof each trunk group 22 may be changed dynamically to provide improvedsignal quality and service as a function of subscriber access to system10.

FIG. 3a is a diagram of an exemplary embodiment of power levels forchannel signals of trunk groups broadcast by a central terminal. Allchannels of each trunk group have the same nominal power level, such as35.7 milliwatts. The composite power level for an exemplary trunk groupconsisting of 28 trunks would thus be one watt. Thus, the subscriberterminals of service area 126 serviced by the central terminal willreceive a weaker signal than the subscriber terminals of service area122 if they are located at a greater distance from the central terminal.Likewise, the subscriber terminals of service area 128 will receive aweaker signal than the subscriber terminals of service areas 122 and 126if service area 128 is at a greater distance from the central terminalthan service areas 124 and 126.

FIG. 3b is a diagram showing system usage and available power leveladjustments for each trunk group to improve signal quality in accordancewith the exemplary embodiment of the present invention shown in FIG. 3a.The number of subscriber terminals for service cell 120 with a centralterminal 122 and three service areas, 124, 126, and 128, is shown inparentheses, e.g. service area 124 has 28 subscriber terminals.

Cell size is established by the path loss between the central terminal122 and the subscriber terminals, by the transmit power of a channelsignal, and by the minimum level at which the receiver achieves anacceptable bit error rate. This minimum level is known as the receiverthreshold. The path loss is affected by environmental factors such astrees and buildings. The transmit power of a channel signal isdetermined by the power amplifier at the central terminal, which couplesthe signals for a predetermined number of channels to the antenna. Thereceiver threshold is related to the receiver design, but may be alteredby intefering signals, such as signals generated by neighboring cells.Thus, cell size may be varied by controlling the transmit power of thesignal channel.

The total available power for each signal is set by the number ofchannels and by the maximum power output of the power amplifier. Powercan be varied to trunk groups of channels to change the sub-cell servicearea. In this manner, subscriber terminals that are physically locatedclose to the central terminal may be served by a sub-cell having asmaller service area, while subscriber terminals that are physicallylocated farther away from the central terminal may be served by asub-cell having a greater service area. In addition, sub-cell size maybe varied as a function of subscriber use to improve fade margin andsusceptibility to interference. At the limit, the number of sub-cellsmay be equal to the number of active subscribers being serviced, andamplifier power may be allocated to a subscriber based upon apredetermined level of power for the location of the subscriber, takinginto account path loss and variables.

FIG. 4a shows the associated power level of the trunk group signalsbroadcast by central terminal for another exemplary embodiment of thepresent invention. The channel power levels of the trunk group forservice area 134 and one of the trunk groups for service area 136 havebeen decreased by 3 dB, and the power level of one of the trunk groupsfor service area 136 has been increased by 3 dB. This change in powerlevel in this exemplary embodiment is achieved by decreasing theamplification power for the channels in two trunk groups by apredetermined amount corresponding to 3 dB, and using the surplus powerto increase the amplification power for the one increased trunk group bya predetermined amount corresponding to 3 dB. In this manner, the fixedtotal magnitude of power amplification may be re-allotted between trunkgroups to increase the effective range of one trunk group whiledecreasing the effective range of other trunk groups.

FIG. 4b shows exemplary locations of subscriber terminals for a servicecell 130 with a central terminal 132 and three service areas, 134, 136,and 138 in accordance with the trunk group power levels shown in FIG.4a. The number of subscriber terminals in each service area is shown inparentheses, e.g. service area 134 has 28 subscriber terminals. Thus,the number and location of subscriber terminals serviced by centralterminal 132 is identical to the number and location of subscriberterminals serviced by central terminal 122 of FIG. 3b. Nevertheless, therelative size of service cell 130 may be greater than that of servicecell 120, as a function of the amplification power used to reach thesubscriber terminals that are located within service area 138.

If the service cell is of the same size and has the same geographicalfeatures as service cell 120 of FIG. 3b, then the subscriber terminalsof service area 138 serviced by central terminal 132 receive a strongersignal than subscriber terminals for the corresponding area 128 of thesystem shown in FIG. 3b. Likewise, the 28 subscriber terminals ofservice area 134 and 28 of the 56 subscriber terminals of service area136 receive a weaker signal than for the corresponding areas of thesystem shown in FIG. 3b.

The allocation of amplification power shown in FIGS. 4a and 4 b may beused when the signal quality of the signal received at subscriberterminals in service area 138 is worse than the signal quality of thesignal received at subscriber terminals in service area 134. Subsequentmodifications may likewise be made if the signal quality of the signalreceived by subscriber terminals in service areas 134 or 136 becomesworse than the signal quality of the signal received by subscriberterminals in service area 138.

FIG. 5a shows yet another exemplary embodiment of the associated powerlevels for trunk group signals broadcast by a central terminal. The 3 dBincrease for the channels of the first trunk group for service area 148is realized in this exemplary embodiment by decreasing the number ofchannels serviced by that trunk group from 28 to 14, thus permitting apower increase of 3 dB. The 6 dB increase for the second trunk group forservice area 148 is realized in this exemplary embodiment byre-allocating the power from the trunk groups for areas 144 and 146, fora 3 dB gain, and by decreasing the number of channels from 28 to 14 andincreasing the power of the remaining channels by 3 dB, for 6 dB oftotal system gain for the channels.

In this manner, the 28 subscriber terminals of service area 148 servicedby the central terminal receive a stronger signal than for thecorresponding areas of the system shown in FIG. 3b, assuming identicalcell geography. The system for increasing the signal strength of thepresent invention may also be used to compensate for signal degradationcaused by environmental factors, multi-path effects, subscriber terminallocations, or other factors.

FIG. 5b shows yet another exemplary embodiment of a service cell 140with a central terminal 142 and three service areas, 144, 146, and 148.The number of subscriber terminals in each service area is shown inparentheses, e.g. service area 144 has 28 subscriber terminals. Thus,the number and location of subscriber terminals serviced by a centralterminal 142 is different from the number and location of subscriberterminals serviced by central terminal 122 of FIG. 3b and centralterminal 132 of FIG. 4b.

FIG. 5b is one example of the changes in the number of subscriberterminals over time in each service area that may occur. The presentinvention allows these changes to be accommodated by re-allocatingamplification power and telecommunications channels to trunk groups,such that improved signal quality may be obtained.

The allocation of amplification power shown in FIG. 5a may be used whenthe signal quality of the signal received at subscriber terminals inservice area 148 is worse than the signal quality of the signal receivedat subscriber terminals in service area 144 and 146. Subsequentmodifications may likewise be made if the signal quality of the signalreceived by subscriber terminals in service areas 144 or 146 becomesworse than the signal quality of the signal received by subscriberterminals in service area 148.

In addition to the three exemplary embodiments shown in FIGS. 3a, 3 b, 4a, 4 b, 5 a, and 5 b, many other suitable combinations of channels pertrunk and amplification power per trunk may be used in order to increasethe signal quality of the communications system of the presentinvention. At the lower limit, a single power level and service area maybe designated to simplify tracking and processing of subscriberterminals. At the upper limit, the location of each subscriber terminalmay be determined and a corresponding minimum power level may beassigned, such that each subscriber terminal has a dedicated servicearea. Additional amplification power may be allocated if available toincrease signal quality. The number and power levels of the serviceareas may also be dynamically assigned so as to increase the signalquality for the average subscriber terminal without substantiallyincreasing the administrative requirements for the system that wouldotherwise be needed if each subscriber terminal had a dedicated servicearea.

FIG. 6 is a flow chart of a method 160 for providing access to atelecommunications system in accordance with one embodiment of thepresent invention. Method 160 may be used to test the signal quality oftelecommunications channels and to adjust the number oftelecommunications channels per trunk group and the amplifier powerallocated to one or more trunk groups in order to improve signalquality.

Method 160 begins at 162, where the signal quality of channels in atrunk group is tested at subscriber receivers. If it is determined thatthe trunk group signal quality is acceptable at step 164, the methodterminates at step 166. Otherwise, the method proceeds to step 168.

At step 168, it is determined whether the number of telecommunicationschannels for the trunk group being tested is less than one-half of themaximum number of allowable telecommunications channels. If the numberof telecommunications channels is less than one-half of the maximum, themethod proceeds to step 170. At step 170, the number oftelecommunications channels for the trunk group being tested isdecreased to one-half of the previous value while the composite powerlevel is maintained. For example, if the number of telecommunicationschannels for the trunk group was 32, it is decreased to 16. The methodthen proceeds to step 172.

At step 172, it is determined whether the signal quality is acceptable.If the signal quality is acceptable, the method proceeds to step 174 andterminates. Otherwise, the method proceeds to step 176. In addition, ifthe number of telecommunications channels for the trunk group beingtested is determined to be greater than one-half of the maximumallowable number at step 168, the method proceeds directly to step 176.

At step 176, it is determined whether power is available for use inother trunk groups, such as if one of the other trunk groups providestelecommunications channels to subscriber terminals that are physicallylocated close to the central terminal. An example of such subscriberterminals would be those within zones 124, 134, or 144 of FIGS. 3a, 4 a,or 5 a, respectively. If a trunk group having this characteristic iscurrently operating at the nominal power level, such as that shown inFIGS. 3b, 4 b, and 5 b, then the power to that trunk group may bedecreased to a level such as the −3 dB level as shown in FIGS. 3b, 4 b,and 5 b.

At step 178, the amplifier power for the trunk group having surpluspower is decreased to the minus 3 dB level. The method then proceeds tostep 180, where the extra amplifier power is allocated to the trunkgroup being tested to increase the signal quality. The method thenterminates at step 182.

In operation, the signal quality for the telecommunications channelscarried by a trunk group is tested. If the signal quality is acceptable,the method terminates. Otherwise, it is determined whether the number oftelecommunications channels for that trunk group may be decreased. Ifthe number of telecommunications channels for the trunk group beingtested may be decreased, this is performed, and it is determined whetherthe signal quality is acceptable. If the signal quality is acceptable,the method terminates.

If the signal quality is not acceptable, or if the number oftelecommunications channels for the trunk group being tested cannot bedecreased, it is determined whether amplification power is availablefrom other trunk groups. If excess amplification power is available fromother trunk groups, the amplification power for those trunk groups isdecreased and the amplification power for the trunk group being testedis increased.

The method of FIG. 6 is exemplary, such that any suitable change inamplification power or number of channels may be utilized. Amplificationpower may be increased or decreased in increments other than +/−3 dB.The number of channels per trunk group may also be increased ordecreased by amounts other than a factor of two.

FIG. 7 is a flow chart of a method 200 for providing access to atelecommunications system in accordance with one embodiment of thepresent invention. Method 200 may be used when a call is placed to orfrom a standby subscriber terminal.

Method 200 starts at step 202, where a service request is received at acentral terminal to place a call to a standby subscriber terminal, orplace a call from a standby subscriber terminal. The method thenproceeds to step 204, where it is determined whether atelecommunications channel slot is presently available in any of thetrunk groups servicing the subscriber terminal. If a telecommunicationsslot is available, the method proceeds to step 206. At step 206, thecall is assigned to the available telecommunications channel slot, andthe method terminates.

If a telecommunications channel slot is not presently available, themethod proceeds to step 208. At step 208, it is determined whether thetelecommunications channels can be increased for one of the trunkgroups. For example, one of the trunk groups may be operating at the +6dB level shown in FIGS. 3b, 4 b, or 5 b. For trunk groups operating atthis level, it is possible to double the number of telecommunicationschannels with a corresponding decrease in effective radiated power levelto +3 dB. This effective radiated power level may be sufficient toovercome any signal quality problems that previously existed and thatcaused the effective radiated power level to be increased. If a trunkgroup has this effective radiated power level, the method proceeds tostep 210.

At step 210, the number of telecommunications channels for an acceptabletrunk group is increased. The standby subscriber terminal is thenassigned to one of the additional telecommunications channels slotsavailable on that trunk group. The method then proceeds to step 212,where the signal quality for the telecommunications channels on thattrunk group is checked. If the signal quality is determined that it beacceptable, the method proceeds to step 213 and terminates. Otherwise,the method proceeds to step 214.

At step 214, it is determined whether the telecommunications channelsfor all trunk groups of the system may be optimized. For example, apredetermined period of time may have elapsed since the last time thetelecommunications channels for all trunk groups have been optimized. Ifit is determined that the telecommunications channels for the trunkgroups may be optimized, the method proceeds to step 218.

At step 218, the power levels for the trunk groups are adjusted. Forexample, it may be determined that the subscriber terminals assigned tothe telecommunication channels of one trunk group are all physicallylocated close to the central terminal, such as the area shown by serviceareas 124, 134, and 144 of FIGS. 3a, 4 a, and 5 a, respectively. Theamplification power for a trunk group having this characteristic isdecreased to a level corresponding to the −3 dB level of FIGS. 3b, 4 b,or 5 b. The method then proceeds to step 220. At step 220, the number oftelecommunications channels for the trunk group that is currentlyoperating at the +3 dB level shown in FIGS. 3b, 4 b, and 5 b, isincreased. Doubling the number of telecommunications channels for such atrunk group, while keeping the composite power of the trunk groupconstant, will cause the effective radiated power level of each channelto drop to the nominal level. The amplification power for this trunkgroup is then increased to bring the effective radiated power level forthe trunk group with the increased number of channels to be increasedback up to +3 dB. The method then proceeds to step 222.

At step 222, the standby subscriber terminal is assigned to theadditional telecommunications channel of the trunk group with theincreased number of telecommunications channels from step 220. Themethod then proceeds to step 224, where the signal quality of all of theeffected trunk groups is checked. If it is determined that the signalquality is acceptable, the method proceeds to step 226 and terminates.Otherwise, the method proceeds to step 216.

If it is determined at step 214 that there are no trunk groups that mayhave optimized telecommunications channels, or if the signal quality ofoptimized trunk groups is determined to be unacceptable at step 224, Themethod proceeds to step 216. At step 216, a busy signal is transmittedto the caller. The method then terminates.

The method of FIG. 7 is exemplary, such that any suitable change inamplification power or number of channels may be utilized. Amplificationpower may be increased or decreased in increments other than +/−3 dB.The number of channels per trunk group may also be increased ordecreased by amounts other than a factor of two.

In operation, a call is placed to a standby subscriber terminal or froma standby subscriber terminal, requiring an additionaltelecommunications channel. If a telecommunications channel isavailable, the call is assigned to that slot. Otherwise, it isdetermined whether a trunk group is operating at an effective radiatingpower level that would allow the number of telecommunications channelsto be increased without affecting the power level of other trunk groups.If such a trunk group is available, the telecommunications channels forthat trunk group are increased, and the call is assigned to one of theadditional telecommunications channels. The signal quality is alsochecked to verify that an acceptable level of signal quality isavailable.

If a trunk group is not available with excess power and channelcapacity, it is determined whether the amplification power for a trunkgroup may be decreased and provided to another trunk group such that thenumber of channels may be increased without a corresponding decrease insignal quality. If this condition exist, the power is reallocatedbetween trunk groups, and the number of telecommunications channels forthe other trunk group is increased accordingly. The standby subscriberterminal is then assigned to one of the additional telecommunicationschannels, and the signal quality is verified to determine whether adecrease in acceptable signal quality has occurred. If the signalquality is determined to be acceptable, the method terminates.Otherwise, a busy signal is transmitted indicating that no availabletelecommunications channels may be created or assigned to the standbysubscriber terminal.

The present invention provides many important technical advantages. Oneimportant technical advantage of the present invention is a method forimproving the quality of data communications that allows the number oftelecommunications channels carried by a trunk group to be dynamicallyincreased and decreased. Another important technical advantage of thepresent invention is a system for transmitting data that allows theamplification power levels of trunk groups to be dynamically assigned.

Although a particular embodiment has been described herein, it will beappreciated that the invention is not limited thereto and that manymodifications and additions thereto may be made within the scope of theinvention as defined by the following claims.

What is claimed is:
 1. A method for improving signal quality comprising: testing the signal quality of a trunk group signal; decreasing the number of telecommunications channels carried by the trunk group if the signal quality is not acceptable and the number of telecommunications being carried by the trunk group is less than one half of the maximum number; and increasing the amplification power level of the trunk group.
 2. A method for improving signal quality comprising: testing the signal quality of a first trunk group signal; decreasing the number of telecommunications channels carried by the first trunk group if the signal quality is not acceptable; increasing the amplification power level of the first trunk group by decreasing the amplification power level of a second trunk group by a predetermined amount; and increasing the amplification power level of the first trunk group due to a processing gain obtained by decreasing the number of telecommunications channels.
 3. A method for improving signal quality comprising: testing the signal quality of a first trunk group signal; decreasing the number of telecommunications channels carried by the first trunk group if the signal quality is not acceptable; increasing the amplification power level of the first trunk group a first amount due to a processing gain obtained by decreasing the number of telecommunications channels; decreasing the amplification power level of a second trunk group by a second amount; and increasing the amplification power level of the first trunk group by the second amount of amplification power made available by decreasing the amplification power level of the second trunk group. 